When a couple of lazy hunter-gatherers are banished from their primitive village, they set off on an epic journey through the ancient world.

Following a ghost invasion of Manhattan, paranormal enthusiasts Erin Gilbert and Abby Yates, nuclear engineer Jillian Holtzmann, and subway worker Patty Tolan band together to stop the otherworldly threat.

Ravaged by the loss of Scooby-Doo in a snowmobiling accident, the Mystery Inc. gang must reunite one final time to plan the funeral and solve one last mystery.